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Internet Journal of the High Pressure School
http://www.unipress.waw.pl/ihps
Proceedings of the III International Warsaw, 13-16 Sept. 1999. Edited
by w. Lojkowski
Ultrastructural Changes in the Cells of Streptomyces sp. R61 Under
High Pressure Treatment
Wiesl/aw Kurzatkowski, Jolanta Solecka, Beata Rozbicka, Monika
Fonberg-Broczek*, Sylwester Porowski*
Laboratory of Actinomycetes and Fungi Imperfecti, National Institute
of Hygiene, Chocimska 24, 00-791 Warsaw, Poland, Tel. (48, 22)
8494051,
E-mail:[email protected]
*High Pressure Research Centre, Polish Academy of Sciences, Sokolowska
29/37, 01-142 Warsaw, Poland
At present, ultra high pressure is proposed to be used for food
conservation. For this reason the aim of this experimental programme
was to test:
1. Ultrastructural changes of ultra high pressure (UHP) treated cells,
2. Killing pressure,
3. UHP mode of killing,
4. Mutagenic effect of UHP.
The hyphal cells were treated separately at 100 MPa, 200 MPa, 300 MPa,
400 MPa, 500 MPa (exponential phase) for 10 min. The ultrathin
sections for electron microscopy were prepared as described previously
[1]. They were examined under a JEM 100 C transmission electron
microscope (JEOL. Ltd., Tokyo, Japan) at 80 kV. The control cells (not
UHP treated samples) showed Procaryotae ultrastructure. The mycelial
cells were surrounded by a cell wall and cross walls were observed.
The cytoplasm was electron opaque, packed with ribosomes. In the
cytoplasm a nucleoid was seen. The space between the call wall and
cytoplasm membrane showed located vesicles of 40 nm in diameter.
Branching of cells was observed. In the cells after 100 MPa treatment
no ultrastructural changes could be seen. After 200 MPa treatment some
of the cells (about 20%), i.e. young cells with delicate cell wall
(one layer of compact and thin cell wall) were disrupted showing no
cytoplasm. About 80 % of cells did not show ultrastructural changes.
At 300 - 500 MPa the ribosomes were crushed. About 80% of cells was
not disrupted. Only two colonies were grown on solid medium after 300
MPa treatment. After 400 - 500 MPa treatment no growth of
microorganism was observed. The colonies after 300 MPa did not show
morphological changes. Further experiments should be done to assay
physiological activities of UHP treated population.
The conclusions of the work are as follow:
1. The UHP treated population showed disrupted young cells and grown
up cells with crushed ribosomes
2. Killing pressure is 400 MPa
3. UHP kills the micro-organisms by: disrupting of cell wall and
cytoplasm membrane of young cells at 200 MPa and; crushing of
ribosomes of grown up cells; disturbing the protein biosynthesis
4. In comparison with control samples, after UHP treatment no
genetically diversified population was observed
5. Further experiments should be done especially to compare
physiological properties of not treated and UHP treated cultures.
References
1. Kurz
atkowski et al. Localization of isopenicillin N synthase in
Penicillium chrysogenum PQ-96. 1991, 35, 517-520
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